This invention relates to a wellhead coupling between overlapping ends of two pipes. The invention also extends to a method of forming a wellhead coupling between two pipes.
Drilling of oil or gas wells typically involves attaching a drilling stack to a conductor pipe or to a surface casing on a temporary basis. Known wellhead connections to surface casings or conductor pipes do not readily accommodate this type of drilling stack attachment, see for example the following exemplary patents—U.S. Pat. No. 4,304,424 to Hanson, U.S. Pat. No. 4,239,266 to Mynhier, U.S. Pat. No. 4,936,382 to Thomas, U.S. Pat. No. 5,299,644 to Ekert, U.S. Pat. No. 5,332,043 to Ferguson, and U.S. Pat. No. 6,834,718 to Webster. There is still a need for a wellhead coupling to surface casing or conductor pipe which will accommodate a drilling stack and which will also allow for quick makeup and disassembly after drilling.